A number of different devices are subject to possible tampering and fraudulent activities. Financial transaction terminals, PIN pads and other related monetary devices are particularly vulnerable and a number of different security arrangements have been proposed to reduce the possibility of tampering. Many of these devices are used in non-secure environments such that protection is more difficult.
Some security arrangements include a switch arrangement associated with a printed circuit board. The switch is maintained in a conducting condition by a mechanical securement force maintaining a split case device secured. If a mechanical arrangement securing the casings is released and the split case opened, the switch moves to a non-conducting condition and the terminal appropriately shutdown and assumes an electronically secure condition.
With prior art tamper switch arrangements there is the possibility of compromising the switch to maintain the switch in a conducting position even though the casing has been opened. In some arrangements it is possible to slide a conducting member into an appropriate position on the circuit board to maintain the conducting condition. Guard conductors are sometimes provided on the circuit board to detect such a conductor. Although this assists in protecting the tamper switch arrangement it is not entirely satisfactory.
Most tamper indicating switches include a spring bias that is compressed when the split casing is in an assembled condition. The spring bias assists in maintaining a conducting condition but reduces the sensitivity of the switch when the casing is opened. Therefore, there is trade off between reliability in maintaining the conducting condition and sensitivity to respond to unauthorized access.
The present invention provides a tamper switch arrangement that accommodates expected tolerances between the two case components while also providing a secure tamper switch.